Traditional and unusual epidermal cysts –a study of 500 cases with review of literature

الملخص EN

Epidermal or epidermoid cyst is a common lesion formed by the down growth and cystic expansion of the epidermis, or of the epithelium forming the hair follicle.

It should be differentiated from trichilemmal and dermoid cysts.

A six and a half years year retrospective analysis of pathological record of cases diagnosed as cases of epidermal cyst in the Department of Pathology, B.

P.

Koirala Institute of health sciences, Dharan, Nepal was done.

A comprehensive list of clinicopathologic findings was noted and the etiology of these cysts reported previously was reviewed.

Total number of cases studied was 500.

The age of the patients ranged from 1.5 to 87 years.

There were 289 (57.8 %) males and 211 (42.2%) females.

Male to female ratio was 1.36 : 1.

The mean age of the cases with traditional epidermal cysts was 50 years.

History of traumatic episode was obtained in 9 (1.8%) cases.

The mean size of traditional epidermal cysts was 1 .7 cm.

Common sites were hair bearing regions.

The epidermal cysts were seen at unusual site also as in breast in 2 (0.4%cases), spleen in 3 (0.6%) cases, subungual region in 1 (0.2%) case, penis in 1 (0.2%) case, palm in 3 (0.6%) cases and sole in 6 (1.2%) cases.

Only in 170 (34%) cases, clinical diagnosis of epidermal cyst was considered in the present study.

Of the cases of traditional epidermal cysts, 11% showed focal absence of a granular layer ; and 23% revealed predominantly compact orthokeratotic cyst content.

A hybrid feature, namely a combined feature of epidermal and so-called trichilemmal keratinization was noted in 11% of the cases of traditional epidermal cysts.

Only 17% of the cases of traditional epidermal cysts showed parakeratosis, whereas parakeratosis was found in all cases of epidermal cysts of the sole.

Foreign body reaction around the cyst wall, namely granulomatous inflammation with foreign body-type multinucleated giant cells, was observed in 1.8% cases of traditional epidermal cysts and 40% cases of epidermal cysts of the sole and 15% cases of epidermal cysts of gluteal region.